The present invention relates to a method of forming an interconnection in a semiconductor device, and relates more particularly, to a method of forming an interconnection in such a device by using a landing pad.
Interconnection technology in a semiconductor device can be divided into two steps, i.e., formation of a contact hole and formation of an interconnection. As a semiconductor device becomes high-integrated, a width of the interconnection line becomes more narrow. Furthermore, when the horizontal size of the contact is reduced, its vertical size is increased, which increases the aspect ratio of the contact. A metal interconnection must be multileveled to enable the enhancing of the operation speed of a device and to provide for a reliable interconnection. In addition, the filling of a contact hole is essential for the planarization of an interdielectric layer.
The filling techniques for filling contact holes in current multilevel interconnection formation processes consist mainly of either one of two methods. Such filling procedures usually involve either a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method.
The PVD method involves depositing a metal such as aluminum in the contact hole by sputtering. However, when the aspect ratio increases because of the reduction of a contact hole size, e.g., to 1 .mu.m or less, the step coverage of a metal deposited on the contact hole is degraded.
The CVD method of filling a contact hole is advantageous for obtaining excellent step-coverage characteristic. However, the CVD method still presents difficulties when the method involves depositing aluminum in the contact hole.
As the aspect ratio of the contact hole increases because of the high-integration of a semiconductor, e.g., as you move to a 256M DRAM and a 1G DRAM, it is difficult to fill the contact hole. This difficulty is present even when a new aluminum reflow method is used to fill the contact hole for the formation of the metal interconnection layer.
Accordingly, due to the difficulties in filling the contact holes, the step-coverage of the metal interconnection is degraded and the contact resistances are increased.